Projects in the coming year will examine the functions of the alveolar macrophage in the pathologic processes resulting from pulmonary virus infections. Viral ingress, uncoating, and replication will be traced ultrastructurally in macrophages and compared with that which occurs in the epithelial cells of the alveoli; endocytosis and digestion will be evaluated in cells harboring replicating viruses to determine whether lysosomal enzyme producton and delivery is diminished in favor of viral protein synthesis. The phagocytosis and killing of bacteria in virus-infected alveolar macrophages will be analyzed by electron microscopy and cytochemistry as well as by direct assay of bacterial viability following phagocytosis by cultures of virus-infected alveolar macrophages.